Focal segmental glomerulosclerosis (FSGS) is a histopathological lesion characterized by scarring (sclerosis) affecting specific sections (segmental) of some glomeruli (focal), accompanied by podocyte injury.1 Although previously considered a single disease, FSGS is now recognized as a heterogeneous condition with diverse etiologies, clinical presentations and responses to treatment. The defining characteristic of FSGS is podocyte injury and loss, which can occur as a primary disorder or as a secondary response to various glomerular stressors. As the disease progresses, localized segmental sclerosis can spread to involve entire glomeruli, eventually culminating in complete glomerular dysfunction.1

Since the 1970s, FSGS has attracted increasing attention due to its role as a leading cause of end-stage renal disease (ESRD) worldwide.2

The morphological classification of FSGS, based on the Columbia system,3 classified the disease into five variants: collapsing, tip, cellular, perihilar, and not otherwise specified. However, relying solely on this framework to make therapeutic decisions proved to be insufficient, as it did not take into account key genetic factors or syndromic presentations, often leading to ineffective treatment. In response, a more comprehensive approach has emerged that considers both clinical and pathological features, redefining FSGS into primary, secondary, genetic and indeterminate forms.4 Primary FSGS is thought to be caused by an unknown circulating factor, in the absence of an identifiable underlying cause. In recent years, several studies have identified anti-nephrin antibodies in a substantial proportion of patients with primary FSGS, suggesting their potential role in the disease.5 These antibodies have been proposed as candidate permeability factors; however, their direct involvement in the pathophysiology of FSGS has not yet been conclusively demonstrated. Other proposed candidates include soluble urokinase plasminogen activator surface receptor (suPAR), apolipoprotein A1b (APOA1b), cardiotrophin-like cytokine factor 1 (CLCF1), and anti-CD40 antibodies.6 In contrast, secondary FSGS develops as a consequence of systemic conditions or external influences, such as viral infections, exposure to toxins or drugs, and glomerular hyperfiltration due to factors such as obesity, congenital renal anomalies, solitary kidney or reflux nephropathy.4 Genetic FSGS, on the other hand, is the result of mutations in genes essential for podocyte function and structural integrity, leading to progressive renal damage.7

Although it is recognized that the overall incidence of FSGS has increased,8 its prevalence varies significantly depending on factors such as geographic region, study period, race, age, and sex distribution. The objective of this review is to critically evaluate prevalence studies published in the last 32 years, providing valuable information on trends, regional differences, and changes in disease rates. By conducting a systematic analysis of the global prevalence and incidence of FSGS, we aim to improve understanding of its epidemiological patterns and suggest future research and health care strategies.

The search strategy followed the preferred reporting items for systematic reviews and meta-analysis (PRISMA) guidelines. A comprehensive search of different information sources was carried out in Medline, Embase, and ScienceDirect databases (1992–2024) was performed using the terms “glomerulonephritis”, “nephropathy”, “kidney disease”, “prevalence”, “incidence”, “epidemiology”, “focal segmental glomerulosclerosis”, and/or “focal segmental glomerulosclerosis epidemiology”, The eligibility criteria for the included studies required them to present original research, were published in English or Spanish, and contained relevant FSGS epidemiological information about trends, epidemiology or incidence of FSGS. Each record was independently reviewed by two researchers based on its title and abstract. In cases of disagreement regarding a study's inclusion, a third researcher evaluated the record and made the final decision. All studies were considered and reviewed from 10 January 2023 to 30 December 2024, regardless of their focus or age group, as long as they contained information according to the inclusion criteria. Exclusion criteria included duplicate publications, insufficient information on incidence, unavailability of full text or incomplete data, and reporting bias. Review articles, transplant registries, conference abstracts, unpublished manuscripts, small sample size (less than 100 patients) in countries with multiple reports and studies on recurrent FSGS were also excluded. Only descriptive statistics were used from the original article. Alternative meta-analyses or advanced statistical models were not performed due to several limitations inherent to the study. These include the use of registry data that may not accurately reflect the general population in some countries, discrepancies in the time periods covered by the various registries, and significant heterogeneity in renal biopsy practices across countries. This variability includes differences in clinical indications for biopsy, procedural strategies, and diagnostic criteria, all of which limit the comparability of the data. We evaluated the language of publication biases, but only 8 articles were discarded as being written in Hebrew, Italian, French, Croatian, German, Chinese, Hungarian and Romanian. Titles and abstracts were reviewed by the authors, and selected studies were evaluated in more detail. We considered frequency and prevalence data reported by the authors, incorporating information from national biopsy registries, case reports, and case series. This work was not registered in PROSPERO because the project had already commenced before registration was considered, and it was later decided to proceed without registration given the stage of progress at that time.

The initial literature search identified 1047 articles, which were systematically selected according to predefined inclusion and exclusion criteria. After this screening process, only 130 original studies met the analysis criteria. A detailed breakdown of the screening process, including the number of articles included and excluded at each stage, is presented in Fig. 1. Across all continents, Asia was the continent with the highest number of reports, 67 in total. Among them, China contributed the largest number of studies with 16, followed by India with 10, Japan with 7 and Pakistan with 4. South Korea and Iran provided 4 studies, while Saudi Arabia, Turkey and Nepal contributed 3 each. Lebanon and Jordan submitted 2 reports, while the United Arab Emirates, Taiwan, Thailand, Oman, Iraq, Bangladesh and Sri Lanka, Kuwait and Singapore contributed 1 study each. Europe provided 33 reports, with Italy leading with 5, followed by Romania with 3, Poland, Spain, the Czech Republic, Denmark, Serbia, Belgium, Germany and Croatia with 2 each. Sweden, France, Cyprus, Lithuania, Estonia, Portugal, Finland, Norway and United Kingdom received 1 report each. The Americas contributed 22 reports, with Brazil leading the way with six studies, followed by the United States and Colombia with five each, Mexico with 2 and Chile, Uruguay, Peru and Canada with 1 each. Africa presented 9 reports, 4 from Nigeria and 1 each from Egypt, South Africa, Morocco, Chad and Sudan. Oceania was the continent with the fewest reports, with only 3, 2 from Australia and 1 from New Caledonia. Table 1 provides an overview of the main characteristics of the studies included in this analysis, and Supplementary Table 1 contains the complete list of studies.

Fig. 1.

PRISMA flowchart depicting the study selection process.

The prevalence of FSGS varies significantly from region to region (Fig. 2). In general, in Asia, South Asian and Middle Eastern countries have a high prevalence, with an average of about 19%, while East Asian countries have lower rates, with an average of 6.5%. In Europe, the prevalence of FSGS remains relatively uniform across countries, with an average of 10%. In the Americas, most countries have a high prevalence. Africa shows a spectrum of prevalence, ranging from moderate to high rates exceeding 20%, but data are limited. A systematic review and meta-analysis in African populations reported a pooled FSGS prevalence of 26.1%. Prevalence rates were similarly high across sub-Saharan regions [West (34.9%), East (33.5%), and South (34.8%)], while notably lower in North Africa (19.8%).9 Oceania has a relatively high average prevalence of 18.5%.

Fig. 2.

Prevalence of FSGS in the studied countries. A blue color scale represents prevalence, with darker shades indicating higher rates. Countries shown in gray lack available prevalence data.

It is important to note that data from many countries are based on limited samples, not numerically representative of the population, which means that actual prevalence rates of FSGS may differ from those reported. In addition, the reported incidence may vary according to the type of healthcare facility, such as primary, secondary or tertiary level hospitals, which may directly influence the observed prevalence of primary and secondary glomerulopathies. Despite these limitations, this study provides valuable information on an estimate of the overall prevalence of FSGS in different countries and, in some cases, highlights trends and changes over time (Fig. 3).

Fig. 3.

Trends in prevalence of FSGS over time in selected countries.

The prevalence of FSGS is influenced by a complex interaction of genetic, dietary, environmental and health factors. An example of this is that in African countries with a high prevalence of FSGS, such as Nigeria and Egypt, a high presence of high-risk variants of the APOL1 gene has been identified.10 In contrast, populations in East Asian countries such as China, Japan and Korea have a lower prevalence of these high-risk APOL1 variants, which may partly explain the lower incidence of FSGS in these regions.11 Dietary patterns also play a critical role. In Western countries, such as the United States and Brazil, diets high in sodium and protein are common. These dietary factors can exacerbate hypertension and hyperfiltration injury, contributing to the higher rates of FSGS observed in these populations.12 In contrast, the diets of East Asian countries, rich in omega-3 fatty acids due to high fish consumption, have anti-inflammatory properties that may provide protective effects against glomerular damage.13 Similarly, the Mediterranean diet, predominant in Southern Europe, is associated with lower rates of cardiovascular and metabolic diseases, key risk factors for kidney disease.14 Additionally, rapid urbanization in countries like India and Brazil has led to lifestyle changes, including increased sedentary behaviors and dietary shifts, which can amplify metabolic risk factors for kidney disease. Notably, countries like Japan and Korea have maintained relatively low obesity rates, which could also contribute to their reduced prevalence of FSGS and other kidney-related conditions.15 It is important to note that disparities in access to genetic testing across countries may also contribute to the higher prevalence of FSGS observed in biopsy samples from lower-resource settings. In wealthier countries, genetic forms of glomerular disease (e.g., APOL1-associated nephropathy) are more often diagnosed through genetic testing, potentially reducing the need for renal biopsy in these cases. As a result, such cases may be underrepresented in biopsy registries from high-resource countries and overrepresented in those from regions with limited access to genetic diagnostics.

Historical reports highlight the global variation in FSGS incidence over time. In 2011, McGrogan et al. documented an incidence of 0.2–1.1 cases per 100,000 person-years,16 while Jegatheesan et al. in 2016 reported an incidence of 1.02 cases per 100,000 person-years.17 In Germany, the incidence increased from 0.1 cases per 100,000 person-years (1990–1997) to 0.6 (2006–2013).18 Similarly, Uruguay reported stable incidence rates across five time periods (1990–2014), ranging between 6.93 and 12.01 per million person-years.19 Italy also observed an increasing trend, with Schena et al. reporting an incidence of 2.3 per million population (pmp) in 1993 and FSGS accounting for 16.6% of nephrotic syndrome cases by 2004.20 Meanwhile, in India, prevalence has varied widely, ranging from 13.1% to 30.6% across different cohorts, reflecting diverse genetic and environmental influences.

Recent trends in FSGS prevalence and incidence reveal changing patterns over time. In North America, Molnár et al. (2023) observed a prevalence of 17.7%, noting a downward trend in the past three years.21 Conversely, Nakagawa et al. (2023) documented stabilization of FSGS incidence in Europe after a decline from 18.6 pmp in 2000 to 14.5pmp in 2013.22 In Latin America, countries like Colombia reported an increase in prevalence from 20.6% in 2013, while in Brazil, prevalence peaked at 55.4% between 2000 and 2005 before declining to 25.8% by 2018.

Age and gender significantly influence FSGS prevalence. Males are predominantly affected, with higher frequencies observed in pediatric populations, particularly among those with corticosteroid-resistant nephrotic syndrome. In contrast, geriatric populations exhibit much lower rates of this podocytopathy.6 A study in Uruguay spanning 25 years (1990–2014) showed FSGS was most prevalent among individuals aged 15–50 years, with declining prevalence in those over 65 years of age.19 Pediatric populations are especially affected, with prevalence rates ranging from 8.5 to 11.6% in Italy, 18.3 to 25.9% in Pakistan, and 28.7% in Colombia, while India reported 9.23%, with 36.2% of cases being steroid-resistant.23–27 A systematic review on the epidemiology of childhood nephrotic syndrome in Africa reported a rise in the prevalence of FSGS from 14% in studies conducted before 1990 to 40% in those published after 1990. Regional differences were also observed, with the highest proportion of FSGS found in Central Africa (33%), followed by Southern (22.8%) and Northern Africa (21.7%). The lowest proportions were reported in Eastern (19.4%) and Western (19.1%) Africa.28

Despite the inherent limitations of data collection and representation, this analysis significantly improves our understanding of global patterns of FSGS. By offering detailed epidemiological insight, it provides clinicians and researchers with a valuable basis for identifying regional trends, underlying risk factors, and variations in prevalence. This information is crucial for tailoring prevention strategies, refining diagnostic approaches, and guiding future research efforts aimed at addressing the global burden of FSGS.

Conceptualization, COC and VCV; Methodology, VCV; Formal analysis, COC, VCV and FALR. Investigation, COC and VCV; Data curation, VCV and FALR; Writing-original draft preparation, VCV, AGG and FALR; Writing-review and editing, COC, VCV, AGG and FALR; Project administration, VCV. All authors have read and agreed to the published version of the manuscript.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

The authors declare no conflict of interest.

Data will be made available on request.